Quasi-experiments in epidemiology: DID, SC, and staggered adoption

Lee Kennedy-Shaffer, PhD

2024-06-18

How Will I Know?

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About Me

  • Assistant Professor at Vassar College/Yale School of Public Health

  • Teach statistical modeling and study design

  • Research focus on infectious disease study design and cluster-randomized trials

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Rise of Quasi-Experiments

Citation for Nobel Memorial Prize in Economic Sciences from 2021

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QEs in Economics and Political Science

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QEs in Epidemiology and Public Health

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QEs in Epidemiology and Public Health

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Citation for Matthay and Glymour (2022)

Considering the Role of Evidence

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  • Allows use of routinely-collected data

  • Evaluates interventions in-context

  • Provides “real world evidence”/population impact

  • Answers questions randomized trials and observational studies cannot

  • But … has threats to internal and external validity

Workshop Plan: Part I

8:45–9:15 Introduction to difference-in-differences

9:15–9:40 Analysis 1: DID of zika impacts

9:40–10:05 Advanced DID and staggered adoption

10:05–10:30 Analysis 2: Advanced DID of COVID-19 vaccine mandates

Workshop Plan: Part II

10:35–11:05 Introduction to synthetic control

11:05–11:30 Analysis 3: SC of Ohio’s COVID-19 vaccine lottery

11:30–11:55 Advanced SC methods

11:55–12:20 Analysis 4: Advanced SC of multiple states’ COVID-19 vaccine lotteries

12:20–12:30 Conclusion

Workshop Goals

  • Understand, interpret, and critique the use of DID and SC in epidemiology

  • Contextualize the assumptions needed for causal inference from quasi-experiments

  • Implement DID and SC analyses and diagnostics/inference in R

  • Gain familiarity with state-of-the-art methods related to DID and SC and identify resources for further exploration

A Note on the Examples

I will focus here on infectious disease examples from published literature with available data. Some issues are specific to ID, while others are not, but they illustrate the points of how to approach these questions.

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Let’s Get To It!

All materials: https://github.com/leekshaffer/Epi-QEs/

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